The principle of generating electricity from the warm air near the ground, channeled into a chimney and ejected at an altitude is known and in particular was the subject of research in Spain and Australia (“solar-tower program”). A 195 m height experimental tower was set up in Manzanares, south of Madrid, and functioned by producing an average power of 50 kW between 1986 and 1989 with a reliability rate of 95%.
The process used consists in making the air pass in a prestressed concrete chimney of straight cross-section, and collecting, by means of a turbine coupled to an alternator, part of the energy of the internal airflow perpetually set in motion by the buoyancy, resulting in the difference between the density of the air located outside and that of the warmer and lighter air channeled inside.
The Australian project was followed a few years later by a 1000 m high tower which had its share of technical difficulties, in particular with respect to the constraints of construction in terms of great height and the seismic requirements as well as a very significant cost of about 500 to 750 million dollars US.
Other similar inventions have since originated all over the world, but have implemented only the buoyancy aspect and presented the major disadvantage of requiring an expensive structure to get the necessary and sufficient height for this operation, which can be estimated from 200 to over 1000 meters.